Trying to catch gravitational waves

March 16, 2011

California State University ; April 5, 2011

Not waiting for a supernova, CSU researchers focus on mirrors

Theoretically, Albert Einstein is a physics icon. So… It doesn’t matter. His theories still get double- and triple-checked. For example, to confirm Einstein’s general theory of relativity, astrophysicists by the score, including some in the CSU, keep trying to spot – if only for a millisecond – gravitational waves. As yet, none has.

Among those contributing to the effort areCSU Fullerton’s Joshua Smith and his students.Along with several others in the CSU, they have been part of an international search party of physicists – called the Laser Interferometer Gravitational Wave Observatory (LIGO). (See LIGO primer excerpt below for introduction to gravitational waves.)While some have suggested that a massive stellar explosion – a supernova – in our galaxy would greatly enhance the prospects for detecting a gravitational wave, Smith’s not inclined to wait.

In a Dec. 1, 2010, post on the OC Science blog, Orange County Register science writer Pat Brennan writes: “Smith…seeks to perfect various components to create an ultra-sensitive, second generation of detectors, expected to be up and running by 2015. Smith and his students are testing new mirrors that could more efficiently concentrate laser light, the key to picking up gravitational waves as they pass through the Earth. If other detectors around the world also catch the same ripples, it would amount to strong verification that gravitational waves exist.” Smith’s research is funded by a three-year $240,000 grant from the National Science Foundation (NSF).

When the CSU met LIGOIn 2000, the CSU’s first official affiliation with LIGO Science Collaboration (LSC) was established by the Elementary Particles and Relativity Group at CSU Dominguez Hills, which remained with the LSC for five years, led by physics Professor Kenneth Ganezer and now-Professor Emeritus Samuel L. Wiley.The CSUDH group worked on optical simulations for searches for gravitational wave bursts. It also developed software for monitoring seismic noise at the LIGO facilities in Hanford, Wash., and Livingston, La. “Our LIGO group involved a few CSUDH undergraduate students, including Nels Pearson,” said Ganezer. “Nels spent a summer – I believe in 2007 – at the LIGO Gin-Gin high-power laser-interferometry facility in the outback of Australia near Perth.”In 2006, with seven oft-cited papers published over a two-year span, Ganezer was named a “hot” researcher in Science Watch.He continues to lead CSUDH’s participation in Super-Kamiokande, a nucleon decay and neutrino baseline oscillation experiment in Japan that the campus has been part of since 1996. Funded by a three-year $330,000 NSF grant, the project continues nearly two decades of NSF support for particle physics and astrophysics research at CSUDH. Ganezer and colleagues recently published a 19-page article in the influential journal Physics in Medicine and Biology on a new X-ray medical imaging technique to improve the diagnosis and monitoring of osteoporosis through the use of spectral information.

When mirrors distortMeanwhile at San José State, Peter Beyersdorf has worked to improve the detection sensitivity of laser interferometry by reducing noise levels. He is currently developing a sensor to monitor the curvature of an optic surface, such as a mirror or beam-splitter.The objective, he reports, is to provide a way to monitor, in real-time, any heat-caused distortions in the curvature of a LIGO mirror.(While working on his Ph.D thesis at Stanford on advanced optical methods for gravity wave interferometry, Beyersdorf met Ganezer through LIGO.)He offered a seminar on LIGO and the search for gravitational waves here (a 16.6Mb .pdf).

Watching atoms spin

Focusing on another aspect of gravity at CSU East Bay, Derek Kimball and his students are using a dual-isotope rubidium magnetometer to search for a hypothetical connection between the nuclear spins of atoms and the mass of the earth. (For Kimball’s explanation of how the machine works and more photos, The first externally funded physics experiment in the history of CSU East Bay, the research program, Kimball reports, “has contributed to tripling the number of physics majors in the past three years; and 16 students, including four women and nine underrepresented minority students, have made meaningful contributions to the project.”

From a Dec. 7, 2010, post at Inside CSUEB: The goal of Kimball’s experiment is to determine whether gravity alone causes those atoms to change the axis about which they spin. “Einstein said it would not,” Kimball explains. “We’re testing whether it could, and we’re doing so 100 times more precisely than it’s ever been tested before.” If the axis does change, Kimball says the theory of gravity will have to be radically revised.”

- Sean Kearns

Background and detailsTo see more of LIGO, check out“Einstein’s Messengers” – a video documentary from NSF.What are gravitational waves? Aprimer from the Hanford, Wash., LIGO facilityoffers this introduction:“The purposes of these detectors is to observe gravitational waves from astrophysical sources at cosmological distances, and to open a new view to the universe by collecting information not accessible by conventional telescopes.According to general relativity theory, gravity can be expressed as a space-time curvature. One of the theory predictions is that a changing mass distribution can create ripples in space-time which propagate away from the source at the speed of light. These freely propagating ripples in space-time are called gravitational waves. Any attempts to directly detect gravitational waves have not been successful yet (in 1998).“Gravitational waves are quite different from electro-magnetic waves.Most electro-magnetic waves originate from excited atoms and molecules, whereas observable gravitational waves are emitted by accelerated massive objects. Also, electro-magnetic waves are easily scattered and absorbed by dust clouds between the object and the observer, whereas gravitational waves will pass through them almost unaffected. This gives rise to the expectation that the detection of gravitational waves will reveal a new and different view of the universe.”